English word soften comes from Middle English soft, Middle English -n

Detailed word origin of soften

Dictionary entry	Language	Definition
soft	Middle English (enm)
-n	Middle English (enm)
soften	English (eng)	(intransitive) To become soft or softer. (transitive) To make less harsh. (transitive) To make something soft or softer.. (transitive) To undermine the morale of someone (often soften up).

Words with the same origin as soften